This invention relates to a carton folding mechanism for a machine for packaging articles in, for example, a sleeve type wraparound carton. Typically the carton is formed from a paperboard blank in which a side wall panel and base panel are hinged together along a fold line. Article apertures, for example, bottle heel retaining apertures incorporating hinged retaining flaps are disposed astride the fold line between the carton panels. The machine in which the mechanism of the present invention may be incorporated includes a conveyor for advancing a blank and the articles to be packaged along a predetermined feed path. The mechanism folds such retaining flaps into their required positions inwardly of the carton. The present invention is concerned with the inward folding of pairs of such retaining flaps associated with each article retention apertures. The flaps of each pair of flaps are engaged and folded inwardly while the adjacent portions of the blank are held against any substantial sidewise movement by suitable guide means.
It is known from EP-0 200 445 to provide article retaining features such as bottle heel retention apertures in the base and side walls of a wraparound carton which receive a heel portion of an article such as a bottle packaged in the carton. Such heel retaining features normally are struck from the side and base wall panels of a wraparound carton and comprise flaps which are hingably attached to the carton panel. In the flat blank the flaps close the apertures which are to provide the bottle heel retention apertures of the carton. When the blank is applied to a group of articles, it is known to open the flaps using a simple finger mechanism to later enable the heel of the article to be received in the aperture created.
A mechanism for achieving this function is disclosed in EP-0 200 445 and comprises a mechanism for engaging and folding a pair of bottle heel retention flaps so that the flaps are folded inwardly of the carton. The folding mechanism includes a pivotal folder comprising a pair of pivotal fingers which are cam actuated so as to execute a folding movement whereby the fingers progressively enter a retention aperture in the blank to fold the flaps and to execute a retracting movement. These folding and retracting movements occur during linear feed movement of the carton blank and the pivotal folder together. The pivotal folders operate sequentially upon a blank to fold open a row of such heel retention flaps and, in a folding section of the machine, move together with the blank through the machine. In order to actuate the pivotal fingers each pivotal folder engages a fixed cam track formed in a cam block and is conveyed through a working path and a return path of a chain and sprocket assembly.